text: //test case checking for line chart
  describe ('the svg',function(){
      var svg = document.getElementsByTagName("svg");
      //checking the creation of svg
      it('svg should be created',function(){
          expect(svg.length).to.equal(1);
      });
      // check the condition that svg have line
      it('svg have rectangles for bar chart',function(){
          expect(document.getElementsByTagName('line')).to.not.be.null;
      });
      //function for getting svg
      function getSvg(){
          return d3.select('svg');
      } 
  });